1. Field of the Invention
This invention relates to a filtration assembly which can be used for culturing microorganisms.
2. Description of the Related Art
A common method of investigating for the presence of microorganisms in a fluid is to pass the fluid through a filter element capable of capturing microorganisms larger than a certain size present in the fluid. After the completion of filtration, the filter element and any microorganisms captured by it are placed in a petri dish containing a nutrient solution. The nutrient solution permeates through the filter element to reach the microorganisms, enabling the microorganisms to be cultured atop the filter element.
The filtration of the fluid containing the microorganisms is typically performed using a filtration assembly including a fluid reservoir connected to a base on which a filter element can be removably disposed. A petri dish for receiving the filter element after filtration forms no part of the filtration assembly, so a separate petri dish is required in order for culturing of microorganisms to take place.
The present invention provides a filtration assembly which can be used both for filtering a fluid containing microorganisms and for culturing microorganisms removed from the fluid by the filtration.
The present invention also provides a method of culturing microorganisms.
According to one form of the present invention, a filtration assembly includes a chamber for holding a fluid sample to be filtered, a fluid port for filtrate in fluid communication with the chamber, a filter support arranged to support a filter element on a flow path between the chamber and the fluid port, and a cover assembly including a lower cover detachably mounted on the chamber and an upper cover detachably mounted on the lower cover. The cover assembly defines a petri dish into which a filter element can be placed for cultivating microorganisms present on the filter element. The ability of the cover assembly to be used as a petri dish makes the filtration assembly highly convenient to use and renders a separate petri dish unnecessary.
In one preferred embodiment, the assembly includes a sample reservoir which defines the chamber, and a base which includes a fluid port and the support surface. The sample reservoir and the base may be permanently connected to each other, or they may be detachable from each other to permit the base to be used separately from the sample reservoir with one of the covers as a petri dish.
In some embodiments, the filtration assembly includes a sample reservoir for holding a fluid sample, and a base for supporting the sample reservoir. The base may be detachably connected to the sample reservoir in a fluid-fight manner without use of a sealing member between the sample reservoir and the base. Because no sealing member is required between the sample and the base, the manufacturing costs of the filtration assembly can be reduced.
In some embodiments, the filtration assembly includes a sample reservoir for holding a fluid sample to be filtered and a base for supporting the sample reservoir. The base includes a fluid port and a skirt surrounding the fluid port for contact with a vacuum manifold of a vacuum filtration assembly. The skirt makes it unnecessary to provide a stopper or an adapter for connecting the base to a vacuum manifold, so the filtration assembly is easy to use.
According to another form of the present invention, a method of culturing microorganisms comprises introducing a fluid sample into a sample reservoir, passing the fluid sample through a filter element communicating with an interior of the sample reservoir to filter the fluid; after filtering the fluid, placing the filter element in a petri dish defined by a cover assembly mountable on the sample reservoir and comprising first and second covers; and incubating microorganisms in the petri dish.
In some embodiments, the method includes disposing a filter element on a filter support surface of a sample reservoir or a base, detachably connecting the sample reservoir to the base in a fluid-tight manner without using a sealing member, introducing a fluid sample into the sample reservoir, and removing fluid which has passed through the filter element from a fluid port of the base.
In some embodiments, the method includes placing a base of a filtration assembly on a vacuum manifold with a skirt of the base contacting an inlet tube of the manifold, and applying suction to an interior of the inlet tube to draw a fluid through a filter element within the filtration assembly and into the manifold.
These and other various aspects of the present invention will be explained in farther detail by the following description and the accompanying drawings.